There are two kinds of people when it comes to yards and plants: those who have gardens and those who have lawns. Oddly enough, gardeners and their various plants often have fewer problems than those growing a lawn of just one kind of grass. For example: Can you overseed and fertilize at the same time?
The problem with keeping a great lawn goes deeper than a few weeds, literally and metaphorically. Your lawn’s soil, the thick root layer known as thatch, and the surface grasses are in many ways their separate beasts, and the only way to keep one healthy is to address them all.
Can You Fertilize and Seed At the Same Time?
Not only can you seed and fertilize at the same time, but it’s also preferable.
Here’s everything you need to know to ensure your lawn has the healthiest seed growth every time.
The Truth About Your Lawn’s Soil
There’s a five-step process for getting the best lawn.
- Step #1: Begin by mowing
- Step #2: Dethatch
- Step #3: Aerate
- Step #4: Fertilize
- Step #5: Seeding
Steps 4 and 5 are where the confusion lies, as these involve fertilizing and seeding your lawn.
Unfortunately, many people forget that steps 4 and 5 go hand-in-hand, and poor seed growth results.
The reason for this issue comes down to the nutritional value of your lawn’s soil.
Grasses aren’t the heaviest feeders, but the shallow root systems can’t get to any nutrients below the surface.
Instead, your grass seeds rely on fertilizer to germinate properly.
In the five-step process, it’s not uncommon to see a person fertilizing as one of the first three steps instead of one of the final two, which can lead to losing much of the nutrition fertilizer offers.
Check The Thatch Before Seeding
When most people hear the word thatch, they think of old roofs.
But this concept of thatch has a basis in nature, and grasses are notorious for forming a thatch layer at the surface.
Thatch is useful because it can help insulate grassroots from sudden temperature changes and is made up of living and dead organic matter deposited on the mat-like root system.
Unfortunately, thatch can also grow so thick that it prevents seeds, water, and fertilizer from permeating the soil beneath.
It’s important to check the thatch layer before seeding and dethatch, if necessary, to ensure your seeds properly sow.
A thick layer of thatch forms a barrier between the grass and the soil.
For example, if you spread grass seed on a lawn with heavy thatch, the seed will not reach the soil.
Without soil contact, your grass will not sprout and establish itself.
Check the thatch layer in your yard and dethatch if necessary before seeding.
Thick thatch prevents grass seed from reaching the soil where it can root.
Rent a dethatcher or power rake to remove thatch buildup before overseeding.
Thatch soaks up water and fertilizer, robbing soil and grass seed nutrients and moisture.
In addition to preventing your grass seedlings from taking root, thick thatch also acts like a sponge, absorbing water and fertilizer before it can penetrate the soil.
Therefore, fertilizing on thick thatch will be far less effective.
Removing thatch before overseeding helps you deliver more lawn starter fertilizer to your grass seeds.
Always Aerate After Dethatching!
Another essential aspect of lawn care, aerating the soil, is essential if you want the best results from seeding.
It loosens the soil, allowing the seeds to take root, and will also help fertilizers absorb before they can be degraded by sunlight.
Aerating is best performed after dethatching your lawn and before seeding.
Choosing The Right Fertilizer For Seeds
Once your lawn has been mowed, dethatched, and aerated, it’s time to grab your seeds and fertilizer, but what fertilizer should you use?
The best fertilizer for overseeding has a higher degree of phosphorus. While it’s used primarily in flowering plants for producing blooms, young grasses rely more on phosphorus for healthy root growth.
Fertilizers for mature lawns contain very little to no phosphorus, preventing germinated grass seedlings from establishing a healthy root system.
Compost
A great way to fertilize your lawn is to use organic compost.
The catch, however, is that compost contains nitrogen primarily in the form of uric acid, which is photosensitive.
If you cut corners and fail to dethatch and aerate the lawn, your compost will be rendered mostly useless because it can’t absorb into the soil properly.
Instead, aim to use it within a few days after aeration for the best results.
Note that applying compost usually works better when done after overseeding, although it will also be effective if used before.
Overseeding and Fertilizing: What Fertilizer To Use?
Any product marked as weed and feed is one type of fertilizer that you should void at all costs when seeding.
These products contain fertilizer and pre-emergent herbicides designed to kill broadleaf weeds and many other unwanted lawn intruders for up to 3 months.
Unfortunately, while these tend to be formulated to kill specific plants, weed and feed products don’t discriminate when it comes to seeds and will kill your grass seed along with the seeds you don’t want.
To avoid this counterproductive fate, apply weed, and feed at least 12 weeks before overseeding and no sooner than 8 weeks after.
When To Fertilize After Overseeding: Before, During, Or After
You can overseed and fertilize in any order, although many choose to do them simultaneously to save time.
In the case of doing these steps separately, they should be done within 3 days of each other.
Fertilizing Before Seeding
This process is about as straightforward as it gets.
Fertilize within a few days after aerating, then follow up within 3 days with the overseeding.
How To Fertilize While Seeding?
Measure out the amount of grass seed and starter you’ll need and mix them thoroughly before adding to the lawn spreader.
You can then use the spreader, as usual, starting with an east-west pattern before switching to north-south for even coverage.
Not only is this method easy, but it can save a lot of time by merging otherwise repeated steps.
Fertilizing After Seeding
Try to overseed within a few days of aerating to ensure the ground is still nice and porous.
Follow this with fertilizer either immediately after or within the next three days.
This is also the best time to rake in some compost, as it will not only fertilize your freshly sown seeds but can provide an insulating layer to help prevent the seeds from drying out.